On average, you will spend approximately 26 years sleeping throughout your life? Just to stress how much that is, let’s reframe it: 26 years equals 9,490 days or 227,760 hours.

That’s a lot of sleep, and you’ve probably already completed a decent portion of that. Yet, the question most of us never really consider is: why? Why do we need sleep?

Why Do We Sleep?

It may be a simple question, but there’s no simple answer. We need sleep for a lot of reasons.

Energy Conservation 

It’s theorized that we sleep so that we don’t run out of energy. Sleeping lowers our metabolism, which in turn saves energy. By getting 8 hours of sleep, we produce a daily energy savings of 35%.

From an evolutionary point of view, this has been very helpful, as it allowed our hunter-gatherer ancestors to reduce energy use during times when it was inconvenient and less efficient to hunt for food. That way,  they’d have more energy left over for when the timing was just right. If you replace the word ‘hunt’ with ‘work’, the same thing applies to most of us today.

Cellular restoration

Another theory explains that sleep allows cells to repair. It helps tissues to grow, muscles to repair, proteins to synthesize, and hormones to be released. There’s a whole load of microbiology behind all of this, but we’re here to explore sleep’s ability to improve our mental state, so let’s move on…

Brain function

Deep sleep allows your neurons to reorganize. To put it simply, neurons are the things that allow us to think and move — everything, essentially. And so, by sleeping and allowing them to recover, we sharpen our ability to learn, solve problems, be creative, and remember things. One of the most fascinating aspects of sleep, however, is how it allows us to process our experiences. You could say it acts as a kind of therapist.

Sleep as a Therapist

Have you ever gone to bed at the end of a tough day feeling upset or angry, only to wake up feeling better? It’s quite common, and this calming, therapeutic process happens thanks to our dreams. At least, that’s what Dr Matthew Walker claims, the director of the Center for Human Sleep Science at the University of California, Berkeley, and author of ‘Why We Sleep’ who specializes in neuroscience and psychology.

He states that throughout the night, we enter stages of deep sleep called REM (rapid eye movement) sleep. During these times, our dreams are the most detailed, vivid, and emotionally charged. Often, these dreams echo the emotional themes or issues we face in our waking lives.

Although this might sound unpleasant, Walker suggests that processing distressing experiences during REM sleep enhances our resilience and mental stability. This is because during the pockets of time we spend in REM, our stress hormone noradrenaline is deactivated. In other words, the brain becomes a stress-free zone — the perfect place to revisit and resolve difficult memories and emotions.

The Research

While this research is ongoing, there is some evidence supporting Walker’s theory of sleep acting as a therapist. Dream researcher Rosalind Cartwright found that in patients with depression, those who dreamed about their painful experiences saw a greater improvement over time. Meanwhile, other studies have focused on army veterans with PTSD. When prescribed medication that suppresses noradrenaline, they report that their PTSD has been alleviated at a faster rate — they recover more swiftly after experiencing trauma.

Dr Walker himself has also run an illuminating experiment. In it, participants were shown disturbing images while their brain activity was analyzed. Twelve hours later, they repeated the process. Half of the participants viewed the first set of images in the morning and the second in the evening. The other half viewed the first set in the evening and the second the very next morning, which allowed them to sleep in between sessions.

From this experiment, Walker uncovered that the second group — those who slept after seeing the disturbing images for the first time — displayed a much smaller fear response to the images when they viewed them the second time around. Clearly, the therapeutic powers of sleep allowed the participants to process their troubled experiences and become more resilient to similar challenges in the future.

Sources